Add missing space in GLSL function list in Differences between GLES2 and GLES3

tutorials/misc/gles2_gles3_differences.rst

@@ -159,7 +159,7 @@ For a complete list of built-in GLSL functions see the :ref:`Shading Language do
 +---------------------------------------------------------------------------------------------+--------------------------------------------------+
 | vec4_type **textureProjLod** ( sampler_type s, vec_type uv, float lod )                     |                                                  |
 +---------------------------------------------------------------------------------------------+--------------------------------------------------+
-| vec4_type **textureGrad** ( sampler_type s, vec_type uv, vec_type dPdx, vec_type dPdy)      |                                                  |
+| vec4_type **textureGrad** ( sampler_type s, vec_type uv, vec_type dPdx, vec_type dPdy )     |                                                  |
 +---------------------------------------------------------------------------------------------+--------------------------------------------------+
 | vec_type **dFdx** ( vec_type p )                                                            |                                                  |
 +---------------------------------------------------------------------------------------------+--------------------------------------------------+